The present invention is generally directed to valve housings for gate valves and the like, and more particularly to a novel valve housing construction and to a method of making the same.
Valve housings of the general type with which the present invention is concerned, and a method of effecting welding of such valve housings by means of directing an electron beam against the parts to be welded, are already disclosed in my prior U.S. Pat. No. 3,473,785 which is incorporated in its entirety by reference.
In that patent I have disclosed how I can make a valve housing for a gate valve or the like by utilizing two forged shell sections which are placed into abutting engagement of their edge faces, thus forming a valve housing. The edge faces are then welded together by an electron beam, and in the interior of the valve housing there is provided a support composed of portions provided on the respective shell sections and to which a seat-forming member is also welded by an electron beam admitted from the exterior of the valve housing.
The construction disclosed in my aforementioned U.S. patent is advantageous for the reasons outlined therein; however, it has been found that further improvements are desirable for reasons of ease of manufacture, and for another reason which is even more important. In particular, it has been found that licensing authorities which must pass on the acceptability of valve housings of such type frequently require that the welded seam be inspected for the quality of the weld by subjecting the housing to an X-ray examination. The construction disclosed in my aforementioned U.S. patent cannot meet these requirements, at least not fully, because in the regions where the edge faces abut there were certain overlaps which existed with portions of the shell sections to which the annular seatforming member was welded, and this overlap made a precise control of the weld quality by X-raying impossible.